Abstract
Sodium carbonate-hydrogen peroxide (SPC, sodium percarbonate) is an oxidizing agent used for bleaching and cleaning. The decomposition of SPC produces water, oxygen and heat. The heat generated by SPC can cause fire accidents. Previous studies reported the effect of water vapor on the decomposition of SPC, but the particular details of the effect have not been revealed. In this study, the effect of the atmospheric conditions (airflow rate and humidity) on the thermal decomposition of SPC is elucidated.
The thermal behaviour was evaluated by placing SPC on a wire basket in an isothermal oven, and a Grewer oven was used to control the temperature of the system. Self-heating of SPC was observed at temperatures above130 °C. Isothermal analysis in the Grewer oven under various atmospheric conditions revealed that a higher airflow rate resulted in a larger temperature rise, and lower humidity resulted in a larger temperature increase at 25% RH. These findings indicate that water vapuor from the surrounding atmosphere and the decomposition product of SPC decreased the rate of thermal decomposition. On the other hand, an additional peak corresponding to the exothermic decomposition of SPC was observed at nearly-saturated humidity at elevated temperature. The experimental results indicate that water vapor enhanced the thermal decomposition because of the deliquescence of SPC under high humidity. These results contribute to the safety management of SPC during storage and manufacture.
